I have the same here.  Roughly 3-4 instances of this message per second in syslog.  I noticed something in the boot log:

Oct 27 09:57:09 ferrari kernel: [   20.545479] PCI: Ignoring BAR0-3 of IDE controller 0000:00:14.1
Oct 27 09:57:09 ferrari kernel: [   20.546417] PCI: Transparent bridge - 0000:00:14.4
Oct 27 09:57:09 ferrari kernel: [   20.546479] PCI: Bus #07 (-#0a) is hidden behind transparent bridge #06 (-#07) (try 'pci=assign-busses')
Oct 27 09:57:09 ferrari kernel: [   20.546482] Please report the result to linux-kernel to fix this permanently
...
...
Oct 27 09:57:09 ferrari kernel: [   20.554087] ACPI: Embedded Controller [EC0] (gpe 16) interrupt mode.
Oct 27 09:57:09 ferrari kernel: [   21.726612] Linux Plug and Play Support v0.97 (c) Adam Belay
Oct 27 09:57:09 ferrari kernel: [   21.726619] pnp: PnP ACPI init
Oct 27 09:57:09 ferrari kernel: [   21.730635] pnp: PnP ACPI: found 12 devices
Oct 27 09:57:09 ferrari kernel: [   21.730680] PCI: Using ACPI for IRQ routing
Oct 27 09:57:09 ferrari kernel: [   21.730682] PCI: If a device doesn't work, try "pci=routeirq".  If it helps, post a report
Oct 27 09:57:09 ferrari kernel: [   21.730809] PCI-DMA: Disabling IOMMU.
...
...
Oct 27 09:57:09 ferrari kernel: [   51.045751] bcm43xx driver
Oct 27 09:57:09 ferrari kernel: [   51.065157] nsc-ircc, chip->init
Oct 27 09:57:09 ferrari kernel: [   51.065173] nsc-ircc, Found chip at base=0x02e
Oct 27 09:57:09 ferrari kernel: [   51.065219] nsc-ircc, driver loaded (Dag Brattli)
Oct 27 09:57:09 ferrari kernel: [   51.065226] nsc_ircc_open(), can't get iobase of 0x2f8
Oct 27 09:57:09 ferrari kernel: [   51.065279] nsc-ircc, Found chip at base=0x02e
Oct 27 09:57:09 ferrari kernel: [   51.065324] nsc-ircc, driver loaded (Dag Brattli)
Oct 27 09:57:09 ferrari kernel: [   51.065327] nsc_ircc_open(), can't get iobase of 0x2f8
Oct 27 09:57:09 ferrari kernel: [   51.065605] pnp: Device 00:09 disabled.
Oct 27 09:57:09 ferrari kernel: [   51.155081] ACPI: PCI Interrupt 0000:00:14.6[B] -> GSI 17 (level, low) -> IRQ 209
Oct 27 09:57:09 ferrari kernel: [   51.167668] ACPI: PCI Interrupt 0000:06:02.0[A] -> GSI 21 (level, low) -> IRQ 233


I know ACPI != APIC, but the message I noticed (I'm not sure yet where it is, I got it in the logcheck mail which I deleted before I saw the APIC error messages) was something along the lines of "noone cares, disabling IRQ 233", which is mentioned above.

Output of lspci:

jtait@ferrari:~$ lspci
00:00.0 Host bridge: ATI Technologies Inc ATI Radeon Xpress 200 (RS480/RS482/RX480/RX482) Chipset - Host bridge (rev 01)
00:02.0 PCI bridge: ATI Technologies Inc RS480 PCI-X Root Port
00:06.0 PCI bridge: ATI Technologies Inc RS480 PCI Bridge
00:13.0 USB Controller: ATI Technologies Inc IXP SB400 USB Host Controller
00:13.1 USB Controller: ATI Technologies Inc IXP SB400 USB Host Controller
00:13.2 USB Controller: ATI Technologies Inc IXP SB400 USB2 Host Controller
00:14.0 SMBus: ATI Technologies Inc IXP SB400 SMBus Controller (rev 11)
00:14.1 IDE interface: ATI Technologies Inc Standard Dual Channel PCI IDE Controller ATI
00:14.3 ISA bridge: ATI Technologies Inc IXP SB400 PCI-ISA Bridge
00:14.4 PCI bridge: ATI Technologies Inc IXP SB400 PCI-PCI Bridge
00:14.5 Multimedia audio controller: ATI Technologies Inc IXP SB400 AC'97 Audio Controller (rev 02)
00:14.6 Modem: ATI Technologies Inc ATI SB400 - AC'97 Modem Controller (rev 02)
00:18.0 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] HyperTransport Technology Configuration
00:18.1 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Address Map
00:18.2 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] DRAM Controller
00:18.3 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Miscellaneous Control
01:00.0 VGA compatible controller: ATI Technologies Inc Radeon Mobility X700 (PCIE)
05:00.0 Ethernet controller: Broadcom Corporation NetLink BCM5789 Gigabit Ethernet PCI Express (rev 11)
06:02.0 Network controller: Broadcom Corporation BCM4318 [AirForce One 54g] 802.11g Wireless LAN Controller (rev 02)
06:09.0 CardBus bridge: Texas Instruments PCIxx21/x515 Cardbus Controller
06:09.2 FireWire (IEEE 1394): Texas Instruments OHCI Compliant IEEE 1394 Host Controller
06:09.3 Mass storage controller: Texas Instruments PCIxx21 Integrated FlashMedia Controller

So the message appears to relate to my wireless NIC.  I copied the firmware over into /lib/firmware/2.6.17-10-generic (extracted for previous kernel versions with bcm43xx-fwcutter), rmmod'd and modprobe'd bcm43xx, but I'm still getting the messages.